Lower preoperative Hounsfield unit values are associated with intra-operative fractures in cementless bipolar hemiarthroplasty.

UNLABELLED: The use of Hounsfield units (HU) from CT scanning to assess regional BMD has been described. Therefore, we evaluated whether HU could be used to identify osteoporosis of the proximal part of the femur. The results showed that HU assessment is associated with the presence of intra-operative fracture during arthroplasty.

INTRODUCTION

The aim with this study was to determine the association of preoperative Hounsfield unit (HU) in hip computed tomography (CT) with intra-operative osteoporotic fracture during cementless hemiarthroplasty.

METHODS

In this retrospective study, we reviewed all patients who underwent cementless bipolar hemiarthroplasty for femoral neck fractures between 2014 and 2016. Patients with intra-operative metaphyseal fractures (n = 25) during surgery were identified from a retrospectively collected patient database and matched with nonfracture controls (n = 75) on the basis of age and sex. The differences between patients with intra-operative fractures and without intra-operative fractures were compared regarding preoperative HU. Correlations of HU value of femur neck with BMD and T scores were determined.

RESULTS

Analysis of HU values at the fracture level showed a significantly lower value in the fracture group than in the controls (1186 vs 1340, p = 0.005). The correlation between HU and BMD of femur neck was significant (r 2 = 0.347; p < 0.001). The correlation between HU of femur neck and BMD of spine was also significant (r 2 = 0.133; p < 0.001).

CONCLUSIONS

HU assessment using preoperative CT scan is associated with the presence of intra-operative fracture during bipolar hemiarthroplasty. We believe that HU values of the proximal femur could be used to assess local bone quality.